Soak wood chunks in water to cover at least 30 minutes.
Prepare charcoal fire in smoker; let burn 15 to 20 minutes. Drain chips, and place on coals. Place water pan in smoker; add water to fill line.
Stir together butter and next 4 ingredients. Divide lemon-butter mixture in half. Crack crab legs, and split lobster tails. Brush lobster and crab with half of mixture; set aside remaining mixture.
Coat rack with cooking spray; place in smoker. Arrange crab legs and lobster tails on rack; cover with grill lid. Smoke crab about 20 minutes and lobster about 45 minutes to 1 hour or until flesh is white and firm.